Lesson objective: Understand that volume can be measured by packing objects with unit cubes

Students bring prior knowledge of tiling squares from 3.MD.5. This prior knowledge is extended to volume as students develop an understanding of packing to find volume. A conceptual challenge students may encounter is understanding the height of the object is equivalent to the layers of cubes that can be packed in a three-dimensional object.

The concept is developed through work with three rectangular prisms, which students will pack with unit cubes to find each prism's volume.

This work helps students deepen their understanding of equivalence because the number of unit cubes in a three dimensional figure determines its volume.

Students engage in Mathematical Practice 7 (Look for and make use of structure) as they pack rectangular prisms with unit cubes to find volume and make sense of the spatial structure of volume. Students must ensure that there are no gaps or overlaps between unit cubes. They also must pay careful attention to the units of measure being used.

**Key vocabulary:**

- cubic
- height
- length
- packing
- unit cube
- cubic inch(es)
- inches cubed
- volume
- width